During production of liquid crystal display panels, a Flexible Printed Circuit (FPC) is desired to transmit signals. FPC is a kind of printed circuit board with high reliability and flexibility. It is made of a base material of polyimide or polyester film, characterized in high wiring density, light weight and thin thickness, and used for signal transmission between a signal generating device and a liquid crystal display module. However, in the case of repeated insertion and extraction, an interface of the flexible printed circuit tends to be damaged due to limitations of the material and appearance of the flexible printed circuit, thereby greatly reducing life span of the flexible printed circuit, causing great waste of materials and thus increasing production cost.